SPP1 and idiopathic CD4 lymphocytopenia: To address this question, and as one of the goals of this study was to identify proteins dysregulated in aqueous humor that could be used as glaucoma biomarkers, we surveyed for differences in the protein levels of GAS6 and SPP1, using commercially available ELISAs in aqueous humor of glaucoma patients in comparison to cataracts and ICL patients.